COMPLETE REDUCTIVE DECHLORINATION OF 1,2-DICHLOROPROPANE BY ANAEROBIC-BACTERIA

The transformation of 1,2-dichloropropane (1,2-D) was observed in anae robic microcosms and enrichment cultures derived from Red Cedar Creek sediment. 1-Chloropropane (1-CP) and 2-CP were detected after an incub ation period of 4 weeks. After 1 months the initial amount of 1,2-D wa s stoichiometrically converted to propene, which was not further trans formed. Dechlorination of 1,2-D was not inhibited by 2-bromoethanesulf onate. Sequential 5% (vol/vol) transfers from active microcosms yielde d a sediment-free, nonmethanogenic culture, which completely dechlorin ated 1,2-D to propene at a rate of 5 nmol min(-1) mg of protein(-1). N o intermediate formation of 1-CP or 2-CP was detected in the sediment- free enrichment culture. A variety of electron donors, including hydro gen, supported reductive dechlorination of 1,2-D. The highest dechlori nation rates were observed between 20 degrees and 25 degrees C. In the presence of 1,2-D, the hydrogen threshold concentration was below 1 p pm by volume (ppmv). In addition to 1,2-D, the enrichment culture tran sformed 1,1-D,2-bromo-1-CP, tetrachloroethene, 1,1,2,2-tetrachloroetha ne, and 1,2-dichloroethane to less halogenated compounds. These findin gs extend our knowledge of the reductive dechlorination process and sh ow that halogenated propanes can be completely dechlorinated by anaero bic bacteria.